<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>呼吸灯</title>
    <style>
        div{
            box-sizing: border-box;
        }
        .content{
            width: 300px;
            height: 500px;
            background-color: #333;
            margin: 0 auto;
        }
        .content .up{
            width: 300px;
            height: 300px;
            border-bottom: 1px solid #ccc;
            padding: 30px;
        }
        .content .up .outer{
            width: 100%;
            height: 100%;
            padding: 30px;
            border-radius: 50%;
            border: 5px solid #ccc;
            
        }
        .content .inter{
            height:100%;
            border: 10px solid #ccc;
            border-radius: 50%;
        }  
        .down {
            color: #f1f1f1;
            text-align: center;
            line-height: 200px;
            font-size: 28px;
        }                          
    </style>
</head>
<body>
    <div class="content">
        <div class="up">
            <div class="outer">
                <div class="inter"></div>
            </div>
        </div>
        <div class="down">呼吸灯 !</div>
    </div>
</body>
</html>